Power cutting tools having a rotating blade or cutting element, such as table saws, miter saws, routers, jointers and shapers, are dangerous. Thousands of operators of these types of cutting tools are severely injured every year. According to data from the United States Consumer Products Safety Commission, roughly 31,000 people are treated in emergency rooms every year for table saw injuries. It is believed that injuries resulting from use of table or cabinet-based power cutting tools other than table saws are equally significant, statistically and in the nature of the injury to the operator, but are not well reported because fewer people own and use such equipment. The physical injury and trauma to an operator's hand and/or fingers is often significant. Injuries occur due to several factors, including lack of understanding by the operator of the equipment and/or characteristics of the wood being cut, inattentiveness, fatigue, work piece kickback and misuse of or misplaced reliance on accessory devices such as push sticks, feather boards, splitters and kerf blades.
As wood is cut, particularly with a table saw, preexisting stresses in the wood are released. The partially cut work piece may move, twist, or bend and the gap or kerf between the cut portions of the wood close together before the work piece is fully cut. With the two separate halves pressing together at the rear of the blade where the saw teeth of the blade are rising up from the table or supporting surface, a work piece can be thrown forwards toward the operator as a projectile. This event is termed a kickback. A second form of kickback may occur if the saw's rip fence or guide fence is misadjusted so as to be slightly closer to the rear of the blade than the front, rather than being parallel to the blade. In this case, the fence can push the wood into the saw blade, leading to a similar result. Splitters and stationary blades mounted behind a rotating saw blade are one type of tool designed to prevent or reduce kickback. However, in practice, such devices do not prevent all cases of kickback and do not address non-kickback related injuries. Moreover, they are limited to use solely with table saws and not other type of powered cutting tools.
The operator can be seriously injured by the thrown work piece. However, serious injury also results to the operator's hand and/or fingers because, prior to the kickback event, the operator is pushing the work piece toward the rotating cutting tool. With the momentum of the pushing motion directed toward the cutting tool, and with the work piece suddenly removed or its physical position unexpectedly altered, the operator's hands can be thrust into the cutting tool. Similar situations can occur when the operator is using accessory aids and when the operator is cutting small pieces of wood with his/her hands positions closely to the cutting tool.
There are different types of cuts performed by powered cutting tools. One type is ripping. A rip cut is performed on a table saw by passing the wood between the blade and a rip fence parallel to the grain of the wood. A cross-cut is the same, but is performed across the grain of the wood. Another type of cut is mitering, and is performed by a specialized miter saw where the blade may be repositioned at an angle relative to the work piece. Mitering is an angle cross-cut. Another type of cut is beveling. Most bevels are rip cuts using a rip fence as a guide with the blade or table tilted to achieve the required angle. Bevel cuts may be made on a miter saw or a table saw. Another type of cut is a dado. A dado cut is done by setting a table saw blade to a cutting depth less than the thickness of the work piece to form a u-shaped cut or groove in the work piece. The dado cut does not go entirely through the work piece. Routing also involves cutting a groove in a work piece. A jointer or shaper cuts or shaves an entire surface of a work piece, such as an edge, to remove or reduce a bow or curve in the work piece. Serious injuries can occur with each of these devices. While all of these devices are different, each has a cutting zone which is the area proximate the moving blade or cutting instrument.
Attempts to develop safety devices for powered cutting tools have been made with limited success. For example, the website www.tablesawaccidents.com shows three safety devices which have limited applicability and usefulness. The device identified as Hand Guard, is a work piece pusher for use in connection with a table saw. It provides a single notch or cut-out at its base which has an adjustable depth to accommodate work pieces of different thicknesses. However, this device is positioned between the saw blade and the guide fence when used. No protection is provided to the operator's hand and use of this device requires the operator's hand to pass by the rotating saw blade. It also limits the narrowness of a cut that can be made on a table saw due to its own width. A second similar device is also shown under the name Push Block. While it saddles and moves along a rip fence, it also provides no protection for the user's hand and only includes a single notch to accommodate a single work piece thickness. In addition, it is not adjustable to accommodate use with guide fences of different sizes and shapes. Further still, an anti-kickback roller device is shown. The device applies a downward pressure on the work piece. As illustrated, one device may be placed before the cutting blade and one positioned following the cutting blade. When deployed in this manner, the devices prevent the use of other needed safety devices, including a work piece pusher and hold down device. Indeed, the Hand Guard and Pusher Block devices depicted on the same web page could not be used with the anti-kickback devices as the forward anti-kickback device prevents the any type of pusher device from moving the work piece completely past the saw blade. It also appears that the post cut anti-kickback device requires the operator to manually lift and position the roller on the work piece, bringing the operator's hand dangerously close to the moving saw blade. Yet another safety device used with table saws is sold under the name SAWSTOP by SawStop, LLC of Tualatin, Oreg. This device is designed to cause a table saw blade to quickly stop, with no injury to an operator's hand. However, this device costs hundreds of dollars and is not designed to be retrofit with existing table saws. Further still, all of the foregoing devices are designed and intended to be used with table saws and do not address the significant and serious injuries created with miter saws, routers, jointers and shapers.